In the rubber industry, an annular surface of a toroidal body is known to be rubber-coated using a rubber-coating system, which coats the annular surface gradually with a strip of elastomeric material of given cross section. To do this, the toroidal body is mounted on a spindle, is rotated about its axis by a motor, and defines, with the spindle, a user unit of said strip.
In known systems of the above type, the strip is normally fed to the annular surface, and hence to the user unit, by a feed unit comprising an extruder for producing elastomeric material in the form of a normally circular-section rod; an applicator roller tangent to the annular surface; and a feed line for feeding the elastomeric material from the extruder to the applicator roller.
The feed line normally comprises a number of powered components arranged in series, and one of which is preferably, though not necessarily, a calender for transforming the rod produced by the extruder into said strip of given cross section. Each of the powered components is normally preceded, along the feed line, by a take-up unit designed to compensate for any difference in travelling speed between the powered component and either the part of the feed line or the extruder preceding the powered component, and to regulate the various travelling speeds to achieve a substantially constant mean travelling speed of the rod produced by the extruder.
For this purpose, known take-up units normally comprise a take-up device, which is supported, in use, by the rod at a bend of varying length, and is movable, alongside variations in the length of the bend, within a range defined by two control sensors located one over the other and a given distance apart.
The presence of a take-up unit of the above type along the feed line poses several drawbacks, in that, both when starting production and in the event of the rod breaking, the free end of the rod must be fed through the take-up unit by hand.
Other take-up units are known, for example from DE 20 2004 009247, which allow automatic feeding of a rod like element, but these take-up units are adapted for use with rod like elements having some axial rigidity only.